ut0rnd.h File Reference

#include "univ.i"
#include "ut0byte.h"
#include "ut0rnd.ic"

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Macros
#define	UT_END_OF_FIELD   257

Functions
UNIV_INLINE void	ut_rnd_set_seed (ulint seed)
UNIV_INLINE ulint	ut_rnd_gen_next_ulint (ulint rnd)
UNIV_INLINE ulint	ut_rnd_gen_ulint (void)
UNIV_INLINE ulint	ut_rnd_interval (ulint low, ulint high)
UNIV_INLINE ibool	ut_rnd_gen_ibool (void)
UNIV_INLINE ulint	ut_hash_ulint (ulint key, ulint table_size)
UNIV_INLINE ulint	ut_fold_ull (ib_uint64_t d) __attribute__((const ))
UNIV_INLINE ulint	ut_fold_string (const char *str) __attribute__((pure))
UNIV_INTERN ulint	ut_find_prime (ulint n) __attribute__((const ))
UNIV_INLINE ulint	ut_fold_ulint_pair (ulint n1, ulint n2) __attribute__((const ))
UNIV_INLINE ulint	ut_fold_binary (const byte *str, ulint len) __attribute__((pure))

Detailed Description

Random numbers and hashing

Created 1/20/1994 Heikki Tuuri

Definition in file ut0rnd.h.

Macro Definition Documentation

#define UT_END_OF_FIELD   257

The 'character code' for end of field or string (used

in folding records

Definition at line 37 of file ut0rnd.h.

Function Documentation

UNIV_INTERN ulint ut_find_prime

(

ulint

n

)

const

Looks for a prime number slightly greater than the given argument. The prime is chosen so that it is not near any power of 2.

Returns

prime

Parameters

n	in: positive number > 100

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UNIV_INLINE ulint ut_fold_binary	(	const byte *	str,
		ulint	len
	)

Folds a binary string.

Returns

folded value

Parameters

str	in: string of bytes
len	in: length

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UNIV_INLINE ulint ut_fold_string

(

const char *

str

)

Folds a character string ending in the null character.

Returns

folded value

Parameters

str	in: null-terminated string

Definition at line 55 of file innodb_utility.c.

UNIV_INLINE ulint ut_fold_ulint_pair	(	ulint	n1,
		ulint	n2
	)		const

Folds a pair of ulints.

Returns

folded value

Parameters

n1	in: ulint
n2	in: ulint

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UNIV_INLINE ulint ut_fold_ull

(

ib_uint64_t

d

)

const

Folds a 64-bit integer.

Returns

folded value

Parameters

d	in: 64-bit integer

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UNIV_INLINE ulint ut_hash_ulint	(	ulint	key,
		ulint	table_size
	)

The following function generates a hash value for a ulint integer to a hash table of size table_size, which should be a prime or some random number to work reliably.

Returns

hash value in: hash table size

Parameters

key	in: value to be hashed

UNIV_INLINE ibool ut_rnd_gen_ibool

(

void

)

Generates a random iboolean value.

Returns

the random value

UNIV_INLINE ulint ut_rnd_gen_next_ulint

(

ulint

rnd

)

The following function generates a series of 'random' ulint integers.

Returns

the next 'random' number in: the previous random number value

UNIV_INLINE ulint ut_rnd_gen_ulint

(

void

)

The following function generates 'random' ulint integers which enumerate the value space (let there be N of them) of ulint integers in a pseudo-random fashion. Note that the same integer is repeated always after N calls to the generator.

Returns

the 'random' number

UNIV_INLINE ulint ut_rnd_interval	(	ulint	low,
		ulint	high
	)

Generates a random integer from a given interval.

Returns

the 'random' number in: high limit; can generate also this value

Parameters

low	in: low limit; can generate also this value

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UNIV_INLINE void ut_rnd_set_seed

(

ulint

seed

)

This is used to set the random number seed. in: seed